Composite anode active material, anode and lithium battery each including the composite anode active material, method of preparing the composite anode active material

Abstract

A composite anode active material, an anode including the composite anode active material, a lithium battery including the anode, and a method of preparing the composite anode active material. The composite anode active material includes: a shell including a hollow carbon fiber; and a core disposed in a hollow of the hollow carbon fiber, wherein the core includes a first metal nanostructure and a conducting agent.

What is claimed is: 
     
       1. A composite anode active material comprising:
 a shell comprising a hollow carbon fiber; and 
 a core disposed in a hollow of the hollow carbon fiber, 
 wherein the core comprises a first metal nanostructure and a conducting agent, 
 wherein the first metal nanostructure is at least one selected from the group consisting of nanoparticle, nanorod, nanowire, nanotube, nanobelt, nanocapsule, and nanotube, and 
 wherein the nanoparticle is silicon nanoparticle, germanium nanoparticle, or tin nanoparticle. 
 
     
     
       2. The composite anode active material of  claim 1 , wherein the core further comprises a pore. 
     
     
       3. The composite anode active material of  claim 1 , wherein the composite anode active material has a pore area of from about 10% to about 90% in a short-axial cross-section. 
     
     
       4. The composite anode active material of  claim 1 , wherein the hollow carbon fiber has an outer diameter of about 500 nm or greater. 
     
     
       5. The composite anode active material of  claim 1 , wherein the hollow carbon fiber has an outer diameter of from about 500 nm to about 5 μm. 
     
     
       6. The composite anode active material of  claim 1 , wherein the hollow carbon fiber has a wall thickness of from about 50 nm to about 500 nm. 
     
     
       7. The composite anode active material of  claim 1 , wherein the first metal nanostructure comprises at least one element selected from the group consisting of silicon, germanium, and tin. 
     
     
       8. The composite anode active material of  claim 1 , wherein the first metal nanostructure is a nanoparticle and has a diameter of from about 10 nm to about 100 nm. 
     
     
       9. The composite anode active material of  claim 1 , wherein the conducting agent comprises at least one selected from the group consisting of a carbon nanostructure and a second metal nanostructure. 
     
     
       10. The composite anode active material of  claim 9 , wherein the conducting agent comprises the carbon nanostructure and the carbon nanostructure comprises at least one selected from the group consisting of carbon nanotube, graphene, carbon nanofiber, fullerene, active carbon particle, carbon nanoplate, carbon onion, and carbon nanoporous. 
     
     
       11. The composite anode active material of  claim 9 , wherein the conducting agent comprises the second metal nanostructure, and the second metal comprises at least one metal selected from the group consisting of silver, gold, copper, aluminum, calcium, tungsten, zinc, nickel, lithium, iron, platinum, and titanium. 
     
     
       12. The composite anode active material of  claim 1 , wherein the first metal nanostructure and the conducting agent in the core are in a weight ratio of about 99:1 to about 50:50. 
     
     
       13. An anode comprising a composite anode active material, the composite anode active material comprising:
 a shell comprising a hollow carbon fiber; and 
 a core disposed in a hollow of the hollow carbon fiber, 
 wherein the core comprises a first metal nanostructure and a conducting agent, 
 wherein the first metal nanostructure is at least one selected from the group consisting of nanoparticle, nanorod, nanowire, nanotube, nanobelt, nanocapsule, and nanotube, and 
 wherein the nanoparticle is silicon nanoparticle, germanium nanoparticle, or tin nanoparticle. 
 
     
     
       14. A lithium battery comprising an anode comprising a composite anode active material, the composite anode active material comprising:
 a shell comprising a hollow carbon fiber; and 
 a core disposed in a hollow of the hollow carbon fiber, 
 wherein the core comprises a first metal nanostructure and a conducting agent, 
 wherein the first metal nanostructure is at least one selected from the group consisting of nanoparticle, nanorod, nanowire, nanotube, nanobelt, nanocapsule, and nanotube, and 
 wherein the nanoparticle is silicon nanoparticle, germanium nanoparticle, or tin nanoparticle. 
 
     
     
       15. A method of preparing the composite anode active material of  claim 2 , the method comprising:
 preparing a first solution comprising a pore-forming material, the first metal nanostructure, and the conducting agent; 
 preparing a second solution comprising a second polymer; 
 electrospinning the first solution and the second solution at the same time to prepare a polymer fiber comprising a core comprising the pore-forming material and a shell comprising the second polymer; 
 stabilizing the polymer fiber to form a stabilized polymer fiber; and 
 calcining the stabilized polymer fiber to obtain the composite anode active material. 
 
     
     
       16. The method of  claim 15 , wherein the pore-forming material is thermally decomposable at a temperature of less than about 1000° C. 
     
     
       17. The method of  claim 15 , wherein the pore-forming material is at least one first polymer selected from the group consisting of polystyrene, polymethylmethacrylate, polyvinyl alcohol, polycarbonate, polyester, polyetherimide, polyethylene, polyethyleneoxide, polyurethane, polyvinylacetate, polyvinylchloride, and a copolymer thereof with polyacrylonitrile. 
     
     
       18. The method of  claim 15 , wherein the pore-forming material comprises at least one selected from the group consisting of SiO 2 , ammonium carbonate, ammonium bicarbonate, ammonium oxalate, titanium dioxide, and zinc oxide. 
     
     
       19. The method of  claim 15 , wherein, in the calcining, the second polymer is carbonized to form a hollow carbon fiber. 
     
     
       20. The method of  claim 15 , wherein the second polymer comprises at least one selected from the group consisting of polyacrylonitrile, polyimide, polyaniline, polypyrrole, and a copolymer of polyacrylonitrile. 
     
     
       21. The composite anode active material of  claim 9 , wherein the conducting agent comprises the second metal nanostructure, and the second metal comprises at least one metal selected from the group consisting of silver, gold, copper, aluminum, calcium, tungsten, zinc, nickel, iron, platinum, and titanium.